Single or Multiple Carbohydrates Sources: which is better for performance?

First, let us be clear on one thing. Performance is all about desire, the desire to push your body to the extreme. However, do not expect great things from your body unless you treat it well. That means getting plenty of sleep, eating a healthy diet, and using a sports drink that delivers what you need when you need it.

Every sports drink out there claims to have the “right stuff” in order to improve your performance, but most of them really do not back up their claims with any real scientific data. First, let us understand the difference between improving your performance and peak performance. I can take a bag of Skittles dissolve them in my water bottle and all of a sudden I have a drink that will improve my performance. In activities over an hour, any source of carbohydrate will help improve your performance compared to water. Therefore, those “scientific” papers that show “Product X” increased their athletes’ performance when they are using water as the control groups are just stating the obvious.

Peak performance is something completely different that unfortunately the majority of us never get to experience. It is when you are good (I mean really good) and is usually reserved to the pros, semi-pros and a few seriously talented amateur athletes. These people are at the top of their sport and when they compete, in order to win, they need every bit of energy their bodies can absorb.

Now you know basically anything is better than water and most of us never achieve peak performance. Let us look at the data on single versus multiple carbohydrate sources, but first a quick chemistry lesson. Carbohydrates are one of the three major sources of calories (the others being protein and fat) in our diets. They are commonly classified as simple sugars (monosaccharides and disaccharides) or complex carbohydrates (oligosaccharides and polysaccharides).

Monosaccharides or “one sugar” are the simplest form of carbohydrates and cannot be broken down into any other sugars. When they are metabolized, they release energy, which is used to fuel the body. Examples of monosaccharides are glucose and fructose. Disaccharides or “two sugars” are (you guessed it) when two monosaccharides are combined together. Examples are sucrose (your common table sugar), which is fructose and glucose joined together and lactose (or milk sugar), which is glucose and galactose (another monosaccharide) joined together.

Complex carbohydrates are oligosaccharides (“few sugars”) and polysaccharides (“many sugars”). There are many different types of complex carbohydrates. The two that are probably most familiar to athletes are glycogen and maltodextrin.

Glycogen is how your body stores glucose and is just thousands of glucose molecules linked together. Glycogen is mainly stored in the liver and muscles. Your body can only store a limited amount of glycogen (about 2000 kcal) so after long periods of exertion without any energy consumption, glycogen stores become depleted (called glycogen debt) and performance significantly decreases. So next time you are on a group run or ride and you see your buddy starting to bonk, hand over one of your gels, and say “it’s time to repay your glycogen debt”. Then just smile at the confused look on his or her face.

Maltodextrin is produced from starch which is polysaccharide consisting of a large number of glucose molecules joined together. It is a very common additive in sports nutrition products, because although technically a complex carbohydrate, it is easily digestible and absorbed as rapidly as glucose. However, unlike glucose, maltodextrin is not very sweet.

So when you look at a nutrition label and it says, for example, carbohydrates 30 grams (g) and sugars 10g, what it means is that out of the total 30g of carbohydrates, 10g are monosaccharides or disaccharides (simple sugars) and the rest (20g) are oligosaccharides and polysaccharides (complex carbohydrates).

Now that your chemistry lesson is over, back to the question, which is better, a sports drink that contains just simple sugars, a sports drink that contains just complex carbohydrates, or a sports drink that contains both. It turns out there is a fair amount of good scientific data on this topic.

Your gut has a limited number of receptors to transport carbohydrates into your bloodstream. By using a drink that contains only one source of carbohydrates (whether simple or complex), you run the risk of overwhelming those receptors, transport will slow down, and this leads to less available energy. In addition, all those extra carbohydrates sitting around will cause water to leave your bloodstream to enter your gut. This situation can lead to abdominal pain, dehydration and decreased performance during exercise. Studies have shown that by using two different sources of carbohydrates (for example, maltodextrin and fructose) that are transported by different receptors you get increased absorption. This will allow you to supply more energy, faster, to metabolizing tissues which translates into better performance.

So although for the most of us Skittles in water is about as much performance enhancement we need, if you push yourself to the extreme and are not sure if your sports drink may be slowing you down learn for yourself what works best for you.  My advice keep it simple and natural.  Check out my recipe for my Pretty Unique Sports Drink.

-Dr. Sal (The Raw Cardiologist)

Is protein really needed in endurance events?

Although, carbohydrates and fatty acids are the primary fuel sources utilized during endurance events, more recently there has been a lot of data to support supplementation with protein during endurance events. In the past few years, clinical trials have clearly demonstrated that a protein/carbohydrate drink enhances performance when compared to a carbohydrate drink alone.

The reason for this is likely manifold and somewhat elusive.  It is unlikely that the small amount of addition calories gained by drinking a carbohydrate/protein drink plays a significant role.  It is more likely because during prolonged exercise, as glycogen levels become depleted, the body undergoes a process called gluconeogensis.  Gluconeogenesis is a process that results in the generation of glucose from non-carbohydrate substrates such as pyruvate, lactate, glycerol, and amino acids.  Gluconeogensis is an energy intensive process that can lead to accelerated muscle breakdown in order to liberate amino acids to drive the gluconeogenic process.  Ingestion of small amounts of protein may help fuel the gluconeogenic process with enough protein to allow the body to avoid having to breakdown muscle.

However, having said this, this is still probably not the primary reason that a protein/carbohydrate drink enhances performance over a carbohydrate alone drink.  Another, probably, more important reason is that a protein/carbohydrate drink appears to help stem cortisol release better than a carbohydrate only drink.  Cortisol is a hormone (often referred to as “the stress hormone”) which is released in large quantities during intense exercise (a very stressful state to the body).

Normal cortisol release has widespread actions that help restore homeostasis (getting back to baseline functioning) after stress.  In the normal situation, this is desirable, but for the endurance athlete it may have grave consequences.  Although, cortisol increases circulating glucose concentrations (in the blood) which is desirable, it does this mainly by supplying amino acids for gluconeogensis by inhibiting collagen formation, decreasing amino acid uptake by muscle, and inhibiting protein synthesis. Also of importance to the endurance athlete is that cortisol also increases gastric acid secretion, potassium loss and is a potent diuretic.  So by using a protein/carbohydrate drink to stem cortisol release, and by supplying a steady stream of protein (or ultimately amino acids) use may spare valuable muscle protein.

A last and more straightforward reason (one purposed by myself) has to do with recovery.  It is widely accepted and practically endurance athlete dogma that protein/carbohydrates supplementation aides in recovery.  The question I have often asked myself is, when does recovery start?  The notion that recovery starts with the cessation of exercise is ludicrous and arbitrary.  For the endurance athlete recovery happens before, during and after exercise.  Recovery is an ongoing process that really has no starting or stopping point.  Let’s face it, exercise is a highly catabolic process. It only makes sense that you want to start rebuilding muscle (or at least slow down muscle breakdown) the minute you start exercising.

As for the issue of how much protein, the answer is no one really knows but it is probably not very much (a few grams/hour).  Protein is much harder to digest than carbohydrates (try eating a steak and than going for a run).  So, if you have too much protein during an endurance event you risk some serious GI distress, too little and you may not get any benefit.

(Reprinted from Triathlete Magazine – September 2008

-Dr. Sal (The Raw Cardiologist)


Is being an endurance athlete dangerous?

In the last few years the endurance community has been beseeched by untimely deaths (Ryan Shay, Steve Larsen) and most recently unexpected retirements (Torbjorn Sindalle).  It makes us all, pro and amateur endurance athletes alike, pause for a minute and think is this life I have chosen the right one?

Well, I am here to tell you as a cardiologist and an endurance athlete I don’t think about it too long because the benefits outnumber any risks.  Ryan Shay, Steven Larsen and Torbjorn Sindalle are the unfortunate exceptions to a very simple rule.  Exercise, don’t smoke, eat a healthy diet, maintain an appropriate body weight (i.e. don’t be fat) and your body will reward you by allowing you to live a healthier, disease free, happier, and more energetic life.

Unfortunately, for most of us, we tend to focus on the exceptions to the rule.  I see this everyday in my practice.  I can be counseling a 30 year old on the horrors of smoking and she tells me about her grandmother who smoked 3 packs a day, lived to be 98, and died peacefully in her sleep.  She says this so emphatically like some how this negates the millions of people who smoke and die of lung cancer, heart disease, and emphysema every year.

Being physically fit outweighs the risks of not being physically fit any day of the week.  However, in saying that, it is definitely not good for your mental well being to be out there on a 50 mile bike ride and wondering if you drew the short straw at birth (genetically speaking) and are destined to drop dead at mile 49.

In a hopeful attempt to ease your mind, let’s talk a little about these three athletes and what you can do to reduce your risk of meeting the same fate.

Ryan Shay likely died of a ventricular arrhythmia (abnormal and generally lethal heart rhythm) caused by an area of scar tissue in the heart.  This area of scar tissue was likely caused by a past infection that had affected the heart muscle.

Every time we get a cold, we pretty much take it for granted that it will run its course and then we will get back to normal.  We typically think of a cold as affecting our eyes, ears, nose and throat but rarely these viruses can also affect our heart.  In the worse case scenario, someone presents with heart failure or in other words the virus (or the body’s immune system response) has attacked the heart leaving it weak, dilated and very susceptible to lethal arrhythmias.   I probably see this happen about a few times a year.

A more insidious pathway however, is probably what happened in Ryan Shay’s case.  At some point in the past he had an infection from which he recovered but unknowingly caused some permanent damage to his heart.  This event set the stage for the presumably lethal arrhythmia from which he eventually died.

Is this to say that if he wasn’t a professional athlete who was constantly pushing his body to the max that he would not have died?  If he had been an overweight, sedentary guy whose idea of exercise was trying to bend all the way over to tie his shoes would he have suffered a different fate?  Although, we can never know for sure, I think the answer is probably no.

Steve Larsen’s death is still somewhat of a mystery to me.  The official autopsy says he didn’t die of a heart attack or a blood clot and according to reports he was having some type of respiratory difficulty in the weeks leading up to his death.  Mostly likely, just like Ryan Shay, he died of a ventricular arrhythmia.  What precipitated the arrhythmia we may never know.

Torbjorn Sindalle is a very different story.  He was born with a bicuspid aortic valve (which he had known about for years) and in the midst of a stellar career with the advice of his doctors he decided to retire.

For those of you who need a refresher course in biology, your aortic valve in the heart valve that sits between your left ventricle and aorta.  Blood, fresh with oxygen, comes from your lungs and goes into the left atrium through the mitral valve and into the left ventricle.   When your heart contracts the pressure (in the left ventricle) causes the aortic valve to open allowing blood to flow into the aorta and out to your body (via arteries).

A normal aortic valve has three cusps (of leaflets) and a bicuspid valve has two.   A bicuspid aortic valve is the most common congenital (means you are born with it) cardiac abnormality that we see and is probably present in 1-2% of the population.

Nature works in very specific ways and unfortunately does not leave very much room for error.  When I think of the natural history of a bicuspid aortic valve, it reminds me of Europe.  I think of the times that I have traveled around Europe looking at great masterpieces and see the effects that nature or in some cases human nature can have on them.  In particular, there is a very famous fountain in Rome that at first glance appears to be very well preserved but when you go around to one side you see this huge indentation in the marble at the base of the fountain.  I remember when I first saw this I was perplexed but after standing there for a little while and seeing that that indentation was the spot where people would come and kneel to say a prayer or ask for a wish, it then became clear.  Millions of people kneeling the same spot day after day, year after year, decade after decade, had worn the marble down to create a very impressive indentation in a pretty resilient substance.  It is pretty hard to fathom it when you are the one kneeling there but nonetheless it is that simple action done a million times over that led to the problem.

A bicuspid valve at birth seems on the surface to work just as well as a normal (tricuspid) valve.  But over time, that very slight difference in the way the valve opens and closes, causes it to slowly wear down over time.  In Torbjorn’s case his bicuspid valve has led to a problem with aortic regurgitation (leakiness).   Normally what happens after the left ventricle contracts and blood goes through the aortic valve into the aorta is the pressure decreases in the left ventricle and causes the aortic valve to slam shut preventing blood from leaking back into the left ventricle. In Torbjorn’s case, after the left ventricle contracts and the aortic valve closes it doesn’t form a tight seal and blood leaks back.  Over time this leads to dilation (enlargement) of the left ventricle and aorta (which causes the valve to leak even more).  Untreated this can increase the risk of heart failure (and sudden death due to a ventricular arrhythmia), or aortic dissection (actual ripping of the aorta) both of which can be quite fatal.

Does that mean that someone who has a bicuspid aorta valve should not exercise?  Absolutely not!!  Torbjorn’s decision to retire from the world of professional endurance sports is not saying that he is going to become a couch potato, sit around and do nothing.  It means that he is no longer going to subject his body to extreme physiological stress that might put him at increased risk of dissecting his already dilated aorta.

So what does this all mean to the average Joe (or Josephine) endurance athlete? I hate to say it but this isn’t the last time that someone well-known and respected pro or amateur athlete will die suddenly.  It will continue to happen, just like people will continue to die in car crashes and planes will suddenly fall from the sky.  However, just like we can do things to reduce the chances of this happening (like wear seatbelts, and have planes get regular scheduled maintenance), we can also do things to make sure that we lessen our chances of dropping dead suddenly on a training ride or at a race.

Here are my suggestions:

Know your family history- Do you have any family members who were seemingly healthy and then died at an early age?  Are all your relatives dying of heart attacks in their forties and fifties?  These are red flags and should be taken seriously.

Do you have high blood pressure, high cholesterol or diabetes in your family?  If you do then you are at increased risk and should be tested.

Get screened. Simple tests like a good physical exam, EKG, echocardiogram, stress test, or cardiac CT can identify a lot of these congenital abnormalities before it is too late.

Don’t assume because you are athletic that you are healthy.  When was that last time you had your cholesterol, blood sugars or blood pressure checked?

Be a smart consumer.  Just because it isn’t banned by the WADA doesn’t mean it is completely safe.  There are a multitude of products (supplements, energy drinks/shots etc…) out there that purported to increase your performance but at what price?  Avoid them.  Their claims are anecdotal (not scientifically tested) and their safety questionable.

Stay well hydrated, well rested, and properly fueled.   When disaster strikes it generally happens when you are at your weakest.  If you are exhausted, dehydrated, depleted of calories and electrolytes you are just upping the ante that something bad will happen.

Don’t fear the doctor.  Your doctor should be your friend.  Let him or her know your fears and concerns so together you both can come up with a plan to help keep you exercising until a ripe old age

Be Happy.  No one lives forever (as far as I know).  If we obsess about all the things that could kill us, most of us would never make it out of the door each day.  Relax, follow the above steps and you should be just fine.

-Dr. Sal (The Raw Cardiologist)

Women as Endurance Athletes: What You Need to Know

Women are very quickly becoming the fastest growing segment of endurance athletes.   Studies suggest that women utilize less glycogen and more fat than men in long, lower-intensity exercise. This makes female athletes particularly well suited for, and may potentially provide an advantage over men in endurance events. Training and competition in endurance events have obvious health benefits, but there are some short-term and long-term negative health consequences, particularly in women, to avoid.

Females clearly have different nutrient requirements than males. Many of these differences are simply based on body size, but others are due to physiological differences.  It is by understanding these physiological differences, that the female endurance athlete can reduce her risk of some immediate and long-term health problems.

Menstrual cycle dysfunction and bone loss

Female endurance athletes who train intensely are at risk for menstrual cycle dysfunction such as amenorrhea (complete lack of menses) or oligomenorrhea (decrease frequency of menses).  This risk likely has to do with a chronic under consumption of calories.  Insufficient caloric intake leads to malnutrition, which increases the likelihood of menstrual dysfunction.  Menstrual dysfunction then leads to hormonal imbalances, which cause a reduction in bone density.  This reduction in bone density in the short-term places the female endurance athlete at increased risk of injuries such as stress fractures.  In the long-term and much, more insidiously these hormonal imbalances can lead to osteoporosis, which is a very common cause of disability and reduced quality of life in older women.  Ensuring that you are eating enough calories and getting enough calcium in your diet may help reduce the risk of menstrual dysfunction and the associated reduction in bone density.


Iron is an integral component of red blood cells (RBCs) and without enough iron, anemia (decreased RBC count) develops which can lead to a reduction in exercise capacity, impaired performance, tiredness, cramping and headaches. In both men and women, iron is lost in sweat, feces, urine, and heel strike hemolysis (the destruction of RBCs caused when the heel hits the ground with force, i.e. running). Due to the added blood loss that women experience with menstruation, iron deficiency is another common problem found in female athletes.

The best way to prevent iron deficiency anemia is to eat a diet that is well fortified in iron and secondarily by wearing well cushioned shoes and running on softer surfaces (to reduced heel strike hemolysis).


  • Eat!  Make sure you are taking in enough calories to meet your energy demands.  If you are unsure how, than is consider talking to a trained sports nutritionist.  You may even consider undergoing testing.  Using oxygen consumption analysis you can find out your basal metabolic rate (how many calories you burn up in a day just being alive) and the amount of calories burned at varying levels of exercise.  You can then use this information to make sure that your energy consumption is always greater than your energy expenditure.  If you do experience menstrual cycle dysfunction, talk to your doctor.
  • Make sure you are getting at least the recommended daily allowance (RDA) of calcium and iron.  Depending on your level of activity, you may need even more than the RDA.
  • Get your blood checked at least yearly to assess calcium levels, make sure that your RBC count is normal and that your iron levels and stores are adequate.
  • Consider bone density testing every few years to make sure your bone density levels are appropriate for your age.
  • Defy expectations, shatter all stereotypes and let your competitive side shine though.


-Dr Sal (The Raw Cardiologist)